Maoricolpus, the New Zealand screw shells, is a genus of sea snails, marine gastropod molluscs in the family Turritellidae, the Turritella snails. Distribution The genus is endemic to New Zealand, and Australia including Tasmania. Shell description The shells are rather large and solid, with many more or less straight-sided whorls. The protoconch has about 2½ smooth whorls, increasing slowly from a small nucleus, and set somewhat mucronately on the rapidly increasing first neanic (or te… (More on Maoricolpus)